The Processing Experimental Study Of Mercury In Wet Flue Gas Desulfurization Waste Water Of The Heat-engine Plant

Mercury has great toxicity, non-natural degradation and strong bioaccumulation,and it caused serious harm to ecological environment and human body health. One of the major sources of mercury is coal-fired power plants wet desulphurization waste water,How to efficiently remove the Hg²⁺ in the desulfurization waste water economy becomes one of the hot research in recent years.This article describes that the method of Hg²⁺ removal in wastewater and Coal-fired power plants in wet desulphurization wastewater treatment Hg²⁺ technology at home and abroad in recent years,and analysis and put forward the suitable removal method of Hg²⁺ in wet desulfurization wastewater of coal-fired power plants.Through the literature, with urea?urea?, carbon disulfide, such as low prices of raw materials, under alkaline conditions was prepared by a new type of dithiocarbamate salts, named DTC-U. At the same time best reaction condition was investigated, and the optimal synthetic conditions were determined as follows: the quantitative water and ethanol as solvent; the molar ratio of urea, sodium hydroxide,carbon disulfide, for n?urea?:n?sodium hydroxide?:n?carbon isulfide?=1:2.2:2.2;carbon disulfide,volume ratio of ethanol to V?carbon disulfide?:V?ethanol?=1:1.5. Reaction temperature of 35?; The reaction time for3 h.Through infrared spectrum proves that the molecule in DTC-U has dithiocarbamate groups.Examines the DTC-U in desulphurization waste water dosing quantity, pH value,reaction temperature, PAC and PAM dosing quantity, reaction time and so on influence on Hg²⁺removal efficiency, through the experiment, found that as the DTC-U dosing quantity increases, Hg²⁺removal rate increases rapidly, when joining the stoichiometric ratio of 2:1 of DTC-U and Hg²⁺,Hg²⁺ removal rate reaches the maximum. DTC-U in pH = 6 to 12 has higher removal efficiency, and the efficiency has little influences by the change of pH.As temperatures rise, Hg²⁺removal efficiency increases, when the temperature reaches 40? the removal rate of Hg²⁺reaches 72.4%, then the removal rate increases with temperature rise slowly. The dosing PAC and PAM is helpful to improve the removal rate of Hg²⁺, at the same with the passage of the reaction time, the removal rate of Hg²⁺ trend from the phenomenon of rising and falling, when the reaction time is 10 min, the removal efficiency of Hg²⁺is highest.In DTC-U on the basis of single factor experiment, the DTC-U with DTCR as the additive to remove Hg²⁺,investigates the ratio between the two, pH value, reaction temperature, PAC and PAM dosing amount, reaction time, the desulfurization wastewater in typical anionic Cl^-, typical of cationic Pb²⁺impact on removalefficiency of Hg²⁺,etc. Experiments found that macromolecular DTCR blends with10% chelating agent DTC-U when dosing quantity 1 times theory has twice before and dosing quantity of removal rate of Hg²⁺ unchanged, thus greatly save the cost,improve the economic benefit of the DTCR. Initial solution pH change on complex matches DTCR has no effect on the removal rate of Hg²⁺. With the increase of reaction temperature, the removal rate of Hg²⁺ gradually increases, when the temperature after more than 40?, the removal rate of Hg²⁺ slows the increase amplitude. Only dosing PAM can further improve the removal rate of Hg²⁺, dosing PAC can restrain the removal rate of Hg²⁺instead.With the passage of the reaction time, the removal rate of Hg²⁺trend from the phenomenon of rising and falling, when the reaction time is 10 min, the removal efficiency of Hg²⁺ is highest. the existence of the Cl^- and the Pb²⁺ in the solution will inhibit the removal efficiency of Hg²⁺.In conclusion,in the preparation of small molecule chelating agent as DTC-U and then associate it with the traditional macromolecular chelating agent as DTCR for compound,these two kinds of additives on remove of Hg²⁺ has high efficiency, better solve the problem of secondary pollution of Hg²⁺ in the desulfurization waste water,and provides theory basis for industrial application for remove of Hg²⁺in wet flue gas desulfurization waste water.